Probe-holding apparatus, sample-obtaining apparatus, sample-processing apparatus, sample-processing method and sample-evaluating method

ABSTRACT

The present invention provides an apparatus for conveying or preparing a specimen for observation, which comprises a probe for conveying a specimen, and temperature control means for controlling the temperature of the sample and the probe whereby the sample does not change during processing or conveyance.

TECHNICAL FIELD

The present invention relates to an apparatus for preparing a specimen.More particularly, it relates to an apparatus for isolating andobtaining a part of a sample of which state and shape may be changedwith temperature change. It also relates to a sample-processingapparatus for preparing a specimen, and a method for evaluating theprepared specimen.

BACKGROUND ART

With the increase of functional devices, demand for cross-sectionalevaluation or fine processing of organic substances such as biologicalmaterials and plastics is increasing. Methods for making cross sectionsof organic materials in order to obtain structural information includecutting with a knife, resin embedding, freeze-embedding, freeze-fractureand ion etching. Usually, for internal structure observation of anorganic matter by optical microscopy, the sample is embedded in a resinand sliced with a microtome.

However, the optical microscope allows only macroscopic observation ofthe cross section and the cut-out position cannot be designated in thismethod, so that it requires an enormous amount of repeating work ofpreparing cross sections in order to observe and analyze the structureat a desired position.

Recently, focused ion beam (FIB) techniques that can process apredetermined site have been developed, where a finely focused ion beamfrom an ion source irradiates a sample for processing it by etching etc.Such FIB etching has become considerably popular, and utilized widelyfor structural analysis or failure analysis of semiconductors or thelike, and for sample preparation of scanning electron microscopy (SEM),transmission electron microscopy (TEM) etc.

Recently, several methods have been proposed to cut out a portion of asample and process it applying manipulation techniques to FIBtechniques. For example, Japanese Patent Application Laid-Open No.H05-52721 proposes a method of cutting out a part of a sample by FIB andthe cut out minute sample is held on a probe, which facilitatesisolation of only the necessary portion for analysis.

Japanese Patent Application Laid-Open No. 2001-345360 proposes a methodof cutting out a minute specimen by using an ion beam and thenbombarding it with another ion beam to reduce the influence of theelement of the first ion beam employed for cutting out.

However, when the sample is a material of which state and shape willchange with temperature such as an organic substance, it is difficult toprepare a minute specimen of a desired-shape using such a probe sincethe temperature of such a probe often becomes higher than that of thesample resulting in heating of the contacted part of the sample.

Thus, the present invention is to provide an apparatus for conveying asample for observation without heat-denaturation.

The present invention is also to provide an apparatus suitable forobtaining a necessary minute piece from a sample.

The present invention is also to provide a sample processing apparatuscapable of efficiently processing a necessary minute piece from a sampleunder temperature control of the sample.

Furthermore, the present invention is to provide a sample evaluatingapparatus and a sample evaluating method for analysis of a cross sectionstructure under temperature control of the sample.

Furthermore, the present invention is to provide a sample-conveyingapparatus capable of conveying a sample for electron microscopicobservation under temperature control of the sample.

DISCLOSURE OF THE INVENTION

The sample-conveying apparatus of the present invention comprises aprobe for conveying a specimen to be observed, and temperature controlmeans for controlling a temperature of the probe whereby the sample doesnot change during conveyance.

The specimen-obtaining apparatus of the present invention comprises astage for supporting a sample; first temperature control means whichcontrols a temperature of the sample; means for isolating a part of thesample; probe moving means for mounting and moving a probe; a probe forobtaining a part of the sample isolated by the isolation means; andsecond temperature control means for controlling a temperature of theprobe.

The sample-processing apparatus of the present invention comprises astage for supporting a sample; first temperature control means forcontrolling a temperature of the sample; ion beam generation means forirradiating the sample with an ion beam; detection means for detecting asignal emitted from the sample in response to the irradiation of the ionbeam; a probe for obtaining a part of the sample processed by theirradiation of the ion beam; a sample table for evaluation; secondtemperature control means for controlling a temperature of the probe;and third temperature control means for controlling a temperature of thesample table.

The sample evaluation apparatus of the present invention ischaracterized in that ion beam irradiation is carried out by using ionbeam generating means and information is acquired by the detection meanswith a sample preconditioned at the predetermined temperature bytemperature-controlling means, the sample is cut out and pasted underthe conditions the temperature of the probe and the sample has beenadjusted at a predetermined temperature by temperature-controllingmeans.

According preferred embodiments, a sample table for evaluation may beprovided separately from the stage. Also the temperature control meansmay be provided with cooling means which cools the sample to atemperature equal to or less than the room temperature. The stage, theion beam generation means, the ion beam detection means, the probe andthe sample table may be provided within a chamber with a controllableatmosphere, and there may be further provided trap means for trappinggas remaining in the chamber.

Also the emission signal may be secondary electrons or secondary ions.Also the detection means may be constituted of a first detector fordetecting secondary electrons and a second detector for detectingsecondary ions.

As described above, according to the present invention, temperature ofthe probe is regulated by the second temperature control means tomaintain the temperature of the sample at a desired temperature, so thata minute specimen can be obtained from a sample of which state and shapeare susceptible to temperature change. Also the first temperaturecontrol means allows to maintain the sample at a desired temperatureduring sample processing, for example, FIB operation. Furthermore, sincethe sample table for evaluation can be temperature-controlled by thethird temperature control means, the sample after fixation to the sampletable can be maintained at a desired temperature. Consequently, changein state or shape of the sample would not occur as in the priortechnology.

The sample processing method of the present invention comprises thesteps of regulating temperature of a sample, a probe and a sample table;sectioning or processing the sample by irradiating a predeterminedportion of the sample with an ion beam from at least two angulardirections relative to a surface of the sample; and connecting the probeto a part of the sectioned sample.

The sample-evaluation method of the present invention comprises thesteps of regulating a temperature of a sample, a probe and a sampletable; sectioning or processing the sample by irradiating apredetermined portion of the sample with an ion beam from at least twoangular directions relative to a surface of the sample; connecting theprobe to a part of the sectioned sample; isolating the sectioned sampleto which the probe has been attached; attaching the isolated sample tothe sample table using the probe; cutting off the probe; and irradiatingthe sample attached to the sample table with an evaluation beam forevaluation to obtain from an emitted signal an image of across-sectioned face of the sample generated by the sectioning orprocessing step.

The present invention also provides a conveying apparatus whichcomprises a conveying member for conveying a sample for observationunder an electron microscope; and temperature regulation means whichregulates a temperature of the conveying member; wherein the temperatureregulation means regulates the temperature of the sample in such amanner that it does not change before and after the conveyance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a focused ion beam processing apparatusbeing an embodiment of the sample processing apparatus of the presentinvention.

FIG. 2 is a block diagram showing a schematic configuration of a samplestage with a temperature controller, an example of a temperature-holdingunit shown in FIG. 1.

FIG. 3 is a flow chart showing a process of a cross section processingof a sample by the focused ion beam apparatus shown in FIG. 1.

FIG. 4 is a schematic view showing a focused ion beam apparatus being anembodiment of the sample evaluation apparatus of the present invention.

FIG. 5A is a schematic view showing sample piece preparation by FIBprocessing from two directions; FIG. 5B is a schematic view showing asectioned sample piece; and FIG. 5C is a schematic view showing thesample piece fixed to a sample table.

FIG. 6A is a schematic view showing a probe attached to a part of asample; and FIG. 6B is a schematic view showing a sample attached to theprobe and cross-sectioned by FIB processing.

FIG. 7 is a block diagram showing a schematic configuration ofprobe-moving means provided with a temperature controller, an example ofprobe-moving means shown in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

Now embodiments of the present invention will be explained withreference to accompanying drawings.

Embodiment 1

FIG. 1 is a schematic view of a focused ion beam processing apparatusconstituting a first embodiment of the sample-processing apparatus ofthe present invention.

The processing apparatus is provided with a temperature holding unit 2on which a sample 1 is fixed and which maintains the fixed sample 1 at apredetermined temperature. The temperature holding unit 2 can beaccommodated in a sample chamber 3.

The sample chamber 3 is provided with an ion beam generating unit 4 forirradiating the sample 1, fixed to the temperature holding unit 2, withan ion beam, an electron detector 5 for detecting secondary electronsemitted from the sample 1 by the ion beam irradiation, gas introducingmeans which enables a film deposition on the sample 1 by the ion beamirradiation, and a probe-holding unit 7 capable of mounting a probe (notshown) for fixing a part of the sample cut out by the ion beamirradiation. The probe-holding unit 7 is preferably a manipulator thatserves as probe-moving means for moving the tip of the probethree-dimensionally. There is also provided a sample table 8 forfacilitating evaluation with another analysis apparatus.

The interior of the sample chamber 3 can be evacuated by a pump (notshown) and can be maintained at a predetermined low pressure, therebyenabling an ion beam irradiation. The interior of the sample chamber 3is preferably maintained at a pressure within a range from 10⁻¹⁰ to 10⁻²Pa.

The ion beam generation unit 4 is used as means for isolating a part ofthe sample by irradiating the sample 1 with the ion beam, and also asprocessing means for processing the sample, for example, to reveal across-section of the sample. It can also be used for scanning ionmicroscopy (SIM) observation. In case of SIM observation, the ion beamgeneration unit 4 and the electron detector 5 serve as informationacquisition means, and the secondary electrons generated when the sample1 is irradiated with the ion beam are detected by the electron detector5 and an image is formed on the basis of detection signals from theelectron detector 5.

The detection signal from the electron detector 5 is sent to a controlunit 9 constituting control means for imaging, and imaging of theaforementioned SIM observation is executed by the control unit 9. Forexample, the control unit 9 receives image information (mappinginformation) in the detection signal from the electron detector 5 anddisplays the obtained image information as an image on an displayapparatus (not shown). In addition, the control unit 9 controls ion beamgeneration in the ion beam generation unit 4 and controls irradiationand scanning of such ion beam onto the sample 1. The beam scanning canbe controlled at the side of the unit 4, or at the side of the unit 2 onwhich the sample is fixed, or both, but control at the side of beamgenerating unit 4 is desirable in consideration of the scanning speed.Also the irradiating position of the ion beam can be so controlled as tofocus it on the probe tip on the sample 1.

The ion beam generation unit 4 may have such a configuration asdescribed in Japanese Patent Application Laid-Open No. H05-52721 or No.2000-217290.

Probe

The probe in the present embodiment is used for obtaining a sample piece(specimen) from a sample by fixing the piece to the probe tip (notshown), and the sample piece is separated from the sample by processing.

Also the probe tip is preferably constituted of a material of asatisfactory thermal conductivity, in consideration of temperaturecontrol. Also the material preferably has a certain resistance to theion beam, since SIM imaging with the FIB is used for confirming theposition of the sample or the probe. Furthermore, the probe tip isconsumed, cut off little by little after the specimen is attached to thesample table. For this reason, it is preferable that the probe or atleast the probe tip can be replaced.

Configuration of the First, Second and Third Temperature Control Means

In the present embodiment, the first temperature control means isprovided with a temperature holding unit 2 capable of temperaturecontrol of the sample. The temperature holding unit 2 is, for example, asample stage provided with a temperature controller. FIG. 2schematically shows a configuration of such a sample stage with atemperature controller.

Referring to FIG. 2, the sample stage with the temperature controller isconstituted of a sample stage 13 having a temperature-varying system 12in a portion on which the sample 1 is fixed, a thermometer 11 a fordirectly detecting the temperature of the sample 1, a thermometer 11 battached to a part of the temperature-varying system 12 to detect thetemperature in the vicinity of the sample 1 fixed to thetemperature-varying system 12, and a temperature control unit 9 a forcontrolling the temperature of the temperature-varying system 12 on thebasis of the temperature detected by the thermometer 11 b, therebymaintaining the sample 1 at a predetermined temperature.

Although not shown in FIG. 2, there is also provided a display unit fordisplaying the temperature detected by the thermometer 11 b, and theoperator can confirm the temperature of the sample 1 displayed on thedisplay unit. Also the temperature control unit 9 a may be soconstructed as to regulate the temperature of the temperature varyingsystem 12 according to the temperatures detected by both thethermometers 11 a and 11 b, and such configuration enables a moreaccurate temperature control of the sample 1. In the present embodiment,the sample table 8 for evaluation is also fixed to the temperatureholding unit 2 like the sample 1, and can be controlled at apredetermined temperature. In such case the first temperature controlmeans serves also as the third temperature control means, but suchconfiguration is not restrictive and there may be provided separatetemperature control means.

The temperature varying system 12 is integrated with the thermometer 11b as a unit in the sample stage 13 to control the temperature in anecessary range. Such unit can be, for example, a high temperature unithaving a heating mechanism such as a heater or a low temperature unithaving a cooling mechanism. It may be, if necessary, a unit having atemperature varying function ranging from low to high temperaturespanning room temperature.

The sample stage 13 can mechanically move, rotate or incline the fixedsample 1 three dimensionally, and thus can move the sample 1 to adesired position for evaluation. The movement control of the sample 1 onthe sample stage 13 is achieved by the aforementioned control unit 9.

The aforementioned cooling mechanism can employ, for example, a Peltierelement or a helium freezer. Otherwise, the aforementioned coolingmechanism may be constructed such that a cooling pipe for a coolant isprovided in the temperature holding unit beneath the area where thesample is fixed so that a coolant such as liquefied nitrogen or waterthermally comes in contact with the temperature holding unit.

Also in order to increase the efficiency of heat absorption for heatgenerated during the processing operation, it is preferable to increasethe contact efficiency between the sample and the cooling unit(temperature holding unit). Such a design can be realized, for example,by preparing a sample holder in such a configuration as to wrap up thesample but not to hinder optical systems employed in processing and inobservation, or by processing the sample in such a shape as to matchthat of the holder so that the sample is held maintaining a maximumcontact area.

Furthermore, it is also possible to cover a non-worked area of thesample with a cooling member. In such case, the cooling member is to beso placed as not to intercept the beam.

Also in this embodiment, a similar temperature holding unit may beincorporated in the probe as the second temperature control means forcontrolling the temperature of the probe. In such case, it may becontrolled by another control unit, but it is also possible to use thecontrol unit 9 for controlling the temperature of the sample and theprobe.

Also the temperature control means for controlling the temperature ofthe probe may be of such a configuration that the probe is connected tothe probe moving means and they are in thermal contact thereby achievingthe temperature control.

Also the probe, the probe moving means and the second temperaturecontrol means may be constructed as shown in FIG. 7. Referring to FIG.7, a probe 40 can be mounted on a probe holder 41 provided with atemperature varying system 12 having a thermometer 11. The probe holder41 provided with the probe 40 is contained in the probe moving means.Also the probe holder 41 can move in the prove moving means 7 accordingto necessity for probe protection, and the tip of the probe 40 canretract in or jut from the probe moving means 7 according to thenecessity.

Also the temperature of the probe may be regulated by the secondtemperature control means, according to the temperature of the sampleregulated by the first temperature control means.

Also the first temperature control means and the second temperaturecontrol means preferably communicate electrically, and the temperatureof the probe is synchronously regulated by the second temperaturecontrol means, according to the temperature of the sample regulated bythe first temperature control means.

The sample and the probe are preferably maintained at substantially thesame temperature by the first and second temperature control means, butthere may also be employed different temperatures.

In such case, it is preferable to maintain the probe at a lowertemperature.

Cross Section Evaluating Method for Sample

A cross section evaluation method of the present invention will beexplained in the following.

FIG. 3 is a flow chart showing a process of evaluation of a crosssection of the sample, utilizing the sample processing apparatus shownin FIG. 1. In the following there will be given an explanation on theprocess of cross sectional evaluation with reference to FIG. 3, and alsoon the control for FIB processing and SIM observation by the controlunit 9 and the temperature control of the sample by the temperaturecontrol unit 9 a according to such process.

First, the sample 1 and the sample table 8 are fixed on a predeterminedposition (temperature varying system 12) of the sample stage 13 (stepS10), and, after an introduction thereof into the sample chamber 3, anevaluation temperature (temperature at which evaluation is carried out)is set (step S11). At the same time, the evaluation temperature of theprobe is similarly set. Once the evaluation temperature is set, thetemperature control unit 9 a controls the temperature at the temperaturevarying system 12, whereby the sample 1 and the sample table 8 aremaintained at such a set evaluation temperature. The temperature of thesample 1 is detected by the thermometer 11 a, and the operator canconfirm, by the detected temperature displayed on the display unit (notshown), whether the sample 1 is maintained at such evaluationtemperature.

In the present embodiment, it is preferred to cool the sample to atemperature lower than the room temperature for processing. Also bycooling to 0° C. or lower, it is possible to solidify water present inthe sample.

In case of employing such a cooling step, it is preferable to first coolthe sample to the room temperature or lower, then to maintain the cooledsample in an atmosphere of a reduced pressure, and to execute theirradiation with the focused beam while absorbing the heat generatedfrom the irradiated surface of the sample and the vicinity thereof,thereby maintaining the shape of the non-irradiated portion.

Also in sample cooling, rapid cooling from the room temperature may beadopted. In such a case, preferably the cooling rate is 40° C./min ormore, whereby. In this manner, it is possible to observe a cross sectionin a rapidly cooled state even when the sample is a mixture of whichdispersibility varies by temperature.

The cooling step is preferably executed before a pressure reducing step.In this manner it is possible to suppress evaporation of the sampleunder a reduced pressure. In case the sample is constituted of asubstance of low evaporation, the cooling may be executed simultaneouslywith the pressure reduction. The probe may be cooled after the pressurereduction.

The cooling step varies depending on the sample to be processed, but, incase of an ordinary organic substance such as PET, cooling is preferablyexecuted within a temperature range of 0 to −200° C., more preferably−50 to −100° C.

If the processing time or the cooling time becomes too long and thesample stays in a low temperature state too long, a gas remaining in thesample chamber or a substance generated in the processing may beadsorbed on the cooled sample, rendering the desired processing orobservation difficult. For this reason, it is preferable to provide trapmeans for adsorbing the remaining gas or the substance generated at theprocessing, and to execute the processing and the informationacquisition while cooling such trap means.

The present invention is advantageously applicable to a case where thesample to be processed is a substance susceptible to heat, such as anorganic substance, particularly a protein or another biologicalsubstance, or a composition containing water. It is particularlypreferable for a composition containing water, since the sample can beworked in a state retaining water.

Since the irradiation of the focused ion beam is executed under areduced pressure, FIB processing of a composition containing water orhighly volatile organic molecules may cause evaporation of water by theheat generated during the processing. Therefore the temperature controlmeans provided in the present invention is highly effective.

For achieving processing and structural evaluation more precisely, it isalso preferable to carry out a step of determining in advance thesuitable holding temperature of processing. In such a case, a sampleequivalent to the sample to be worked is employed as a reference, and isworked at various temperatures, and preferred holding temperature isdetermined by investigating the relation between the damage in theworked portion and the cooling temperature.

After the sample 1 is confirmed to be maintained at the evaluationtemperature, the surface of the sample 1 is subjected to SIM observationunder constant monitoring of the temperature of the sample 1 (step S12).In such SIM observation, there is employed a weak ion beam forobservation, and the sample 1 is scanned by the ion beam from the ionbeam generation unit 4 under the control by the control unit 9 on theion beam irradiation from the ion beam generation unit 4 and on themovement of the sample stage 13. Also in synchronization with suchscanning, the electron detector 5 detects the secondary electrons, andthe control unit 9 displays a SIM image on the display unit (not shown),based on a detection signal of such secondary electrons. In this manner,the operator can observe the SIM image of the surface of the sample 1.

Then a cross section evaluating position (position subjected tocross-section evaluation) is precisely determined from the imageobtained by the SIM observation of the surface of the sample 1 (SIMimage displayed on the aforementioned display unit) (step S13), and thusdetermined cross section evaluating position is further subjected to aSIM observation with a processing beam (step S14). In such SIMobservation, the sample 1 is scanned within the range of the crosssection evaluating position by the ion beam from the ion beam generationunit 4 under the control by the control unit 9 on the ion beamirradiation from the ion beam generation unit 4 and on the movement ofthe sample stage 13. Also in synchronization with such scanning, theelectron detector 5 detects the secondary electrons, and the controlunit 9 displays a SIM image on the display unit (not shown), based on adetection signal of such secondary electrons. In this manner, theoperator can observe the surface SIM image of the cross sectionevaluating position determined in the step S14. Also after thedetermination of the cross section evaluating position and before theSIM observation with the processing beam, if necessary, a gas isintroduced from the gas introducing means 6 for depositing a protectivefilm on the periphery of the sample 1 including a worked portion.

Then FIB processing conditions are set (step S15). In such setting ofthe FIB processing conditions, the area and position to be sectioned isdetermined on the SIM image obtained in the surface SIM observation ofthe step S14, and there are also set cross section processing conditionsincluding an accelerating voltage, a beam current and a beam diameter.The cross section processing conditions include crude processingconditions and fine processing conditions, both of which are set at thisstate. The crude processing conditions have a beam diameter and anenergy amount larger than those in the fine processing conditions. Thearea and position to be sectioned may be determined on the SIM obtainedwith the observing ion beam in the step S12, but, in consideration ofprecision, it is preferable to determine on the SIM image utilizing theion beam to be employed in the actual processing.

In such processing from the surface, an ion beam is irradiated in anamount necessary for cutting onto the area and position to be sectioneddetermined in step S15, where the control unit 9 controls the ion beamgeneration unit 4 to the preset processing conditions and also controlsthe movement of the sample stage 13. In this operation, in order toisolate a part of the sample, including the portion necessary forevaluation, most of the periphery of the cut-out sample, seen fromabove, is worked deeper than the portion for evaluation, only leaving aportion which can be cut off by a minimum processing thereafter.

After the processing from the surface, the surface of the sample 1 issubjected to a SIM observation, and there is confirmed, on the imageobtained by the SIM observation (SIM image), whether the processing hasproceeded close to the desired position (step S17). Then the sample isinclined together with the stage (step S18), and a cross sectionprepared by the processing from the surface is subjected to a SIMobservation with an observing beam, in order to confirm the shape of thesurface (step S18).

In case the processing has not proceeded close to the desired depth, thestage is returned to the original inclination and the foregoing stepsS16 to S19 are repeated.

Then FIB processing conditions from the direction of cross section areset (step S20). In such setting of the FIB processing conditions, asectioned area and a sectioned position are determined on the SIM imageobtained in the cross sectional SIM observation of the step S19, andthere are also set cross section processing conditions including anaccelerating voltage, a beam current and a beam diameter. Then there isexecuted an FIB processing from the cross sectional direction (stepS21). The cross sectional direction means an angular direction differentfrom the surface of the sample, and allowing observation of the crosssection formed by the FIB processing from the sample surface. Therefore,it need not be perpendicular to the cross section surface. In suchprocessing from the cross sectional direction, most parts are isolatedfrom the sample, only leaving the aforementioned portion which can becut off by a minimum processing.

Then, after the sample is inclined to the original angle (step S22), aweak beam for observation is irradiated from the surface, therebyexecuting a surface SIM observation of the sample 1 (step S23). Based onthe surface SIM image in the step S23, the probe is moved onto a minutesample piece to be removed (step S24). Then it is confirmed that theprobe is contacted with the minute piece for example by a contrastchange in the SIM image, a gas is introduced by the gas introducingmeans 6 and an FIB beam is irradiated in a position including thecontact portion between the probe and the minute piece to deposit afilm, thereby adhering the probe (step S25).

Then the aforementioned portion which can be cut off by a minimumprocessing is cut off with a processing beam (step S26) whereby thesample piece is isolated from the sample 1 and remains in a state fixedto the probe.

In this state, since the sample including the sample piece and the probeare maintained at equivalent temperatures by the step S11, thetemperature of the sample piece scarcely changes at least by the contactof the probe. If the temperature of the probe and the sample issignificantly different, the temperature of the sectioned sample piecewill change close to the temperature of the probe. Thus, by confirming,prior to the contact of the probe, that the temperature of the sampleand the probe is almost the same, it is possible to prevent thetemperature change in the sample piece.

Thereafter, the probe with the sample piece adhered thereto is movedonto the evaluating sample table 8 (step S27), then, after confirmationthat the sample piece is in contact with the sample table 8, a gas isintroduced from the gas introducing means 6 and an FIB beam irradiationis executed to adhere the sample piece to the sample table 8 (step S28).Thereafter a part of the probe is cutoff by an ion beam (step S29),whereby the sample piece is transferred to the sample table 8. Also, ifnecessary, the sample stage 13 is inclined to cause an inclination inthe sample table 8, and a film deposition is executed by a gasintroduction and an ion beam irradiation thereby reinforcing theadhesion between the sample piece and the sample table 8. Also in orderto facilitate the adhesion and the cutting-off of the probe, the tip ofthe probe is not in a position perpendicular to the sample surface norto the cross section of the sample but is inclined by a certain angle,thereby enabling a positional confirmation by the SIM image and aprocessing with the ion beam.

After the sample piece is adhered to the sample table 8 for evaluationas explained above, a SIM observation of the sample surface is executedby an observing beam (step S30) to confirm the adhesion in a desiredposition, and subsequently an FIB processing (finish processing) isexecuted (step S31). In the finish processing, the sample piece fixed tothe sample table 8 by the process up to the step S29 is irradiated withan ion beam of an amount necessary for the finish processing, under thecontrol by the control unit 9 on the ion beam generation unit 4 with theaforementioned finish processing conditions and on the movement of thesample stage 13. Such finish processing allows preparation of a smoothcross section suitable, for example, for an observation of a highmagnification under a transmission electron microscope.

Finally a SIM observation of the sample surface (step S32) is executed,in order to obtain an evaluation sample of a desired thickness.

In case the processing has not been made to the desired thickness, theaforementioned steps S31 and S32 are repeated.

Also a cross section for the scanning electron microscope can beprepared by a finish processing of one surface.

As explained in the foregoing, the sample processing apparatus of thepresent embodiment can constantly maintain the sample 1 to be evaluated,the probe and the sample table 8 for evaluation at a set temperature, sothat the sample 1 is not changed in the state or the shape thereof.Consequently even a sample easily damaged by processing can be exactlyevaluated for a fine structure.

The cross section processing method in the foregoing embodiments iseffective for analyzing, at a desired temperature, samples on varioussubstrates such as glass including a polymer structure, microparticles,a polymer structure containing liquid crystal, a particle dispersionstructure in fibrous materials or a material causing a temperaturetransition. It is also effective for a sample easily damaged by an ionbeam.

Also the aforementioned probe moving means may be provided in pluralunits in the apparatus.

Embodiment 2

In the present embodiment, in addition to the configuration of theembodiment 1, there is provided, as shown in FIG. 4, trap means 14 forpreventing re-deposition of a residual gas in the sample chamber 3 or asubstance generated in the processing onto the sample 1.

The trap means 14 is constituted, for example, of a metal of asatisfactory thermal conductivity, and is maintained, during the coolingof the sample 1, at a temperature equal to or lower than that of thesample 1.

The present embodiment provides an effect of preventing deposition of animpurity onto the sample 1, in case the sample 1 is worked and observedin a state maintained equal to or lower than the room temperature. Forexample, in case of the above-explained FIB-assisted deposition, theremay result a layer of impurity between the deposition layer and theworked sample, whereby a desired function is hindered, but the presentembodiment suppresses formation of such an impurity layer by the trapmeans 14.

The trap means 14 is provided, in a state where the sample stagesupporting the sample 1, the ion beam generation unit 4, the electrondetector 5, the gas introducing means 6 and the probe are positioned, insuch a position as not hindering the detection system and the beamsystem at the processing. The trap means 14 is preferably provided in aposition not hindering such detection and processing and as close aspossible to the sample 1, in order to improve the trapping efficiency.Also the trap means 14 may be provided in one or more positions in thesample chamber 3 maintained at a low pressure.

Embodiment 3

In the embodiment, there will be explained a case of utilizing theapparatus of the present invention as a cross section processingapparatus in the production process of a liquid crystal displayapparatus or an organic semiconductor. More specifically, there will beexplained an embodiment of executing a temperature control of a sampleof a relatively large area.

In case of exactly evaluating a cross sectional state in a part of alarge-sized sample such as a glass substrate coated with liquid crystal,for use in a large-sized liquid crystal display apparatus, thetemperature control may be executed either in a local area in thevicinity of a worked portion, or over the entire substrate. In case oftemperature control of the entire substrate, a coolant pipe for passinga coolant is provided in a position of the temperature holding unitunder the surface supporting the sample, thereby cooling the entireholder.

EXAMPLES

In the following, there will be explained actual examples of crosssectional evaluation of samples with the sample evaluating apparatus ofthe foregoing embodiments.

Example 1

In this example, there was employed a sample-processing apparatus forcross sectional observation, shown in FIG. 1. The temperature holdingunit 2 was constituted of the sample stage with the temperaturecontroller as shown in FIG. 2, incorporating a unit with a lowtemperature-varying system, and a cross sectional evaluation of asample, bearing a polymer structure (polymerizable monomers HEMA, R167,HDDA polymerized together with liquid crystal) containing liquid crystal(two-frequency drivable liquid crystal DF01XX manufactured by ChissoInc.) on a glass substrate, was executed in the following process.

The sample was fixed with a carbon paste to a unit with a lowtemperature-varying system, and the unit was set on the sample stage 13.The sample stage 13 with the sample was inserted in the sample chamber3, which was then evacuated to a predetermined low pressure.

Then the evaluation temperature was set at −100° C., and it wasconfirmed that the sample was maintained at such evaluation temperature.A surface SIM observation was executed on an area including a crosssectional observation portion of the sample, under constant monitoringof the sample temperature. Based on an image obtained by the surface SIMobservation, an approximately central portion of the sample wasdetermined as a cross sectional observation portion.

Then the determined cross sectional observation portion was irradiatedwith an ion beam to acquire a SIM image. The ion beam in this operationwas a very weak one of the observation mode. More specifically, therewere employed a gallium ion source, an acceleration voltage of 30 kV, abeam current of 20 pA and a beam diameter of about 30 nm. A crosssection processing position was designated on the acquired SIM image.

Then the designated cross section processing position was subjected toan FIB processing (surface processing).

More specifically, there were employed an acceleration voltage of 30 kV,a beam current of 50 pA and a beam diameter of 300 nm to form, in thecross sectional processing position, a rectangular recess of a squareshape of 40 μm and a depth of 30 μm. Then an L-shaped recess was formedsimilarly with a processing beam so as to be connected with therectangular recess, leaving an evaluation portion. Then the sample wasinclined, and, after a confirmation of the processing to the desiredposition with a weak beam for SIM observation, the bottom portion of theremaining evaluation portion was subjected to an FIB processing (crosssection processing). The inclining angle was about 60°. FIG. 5A is aschematic view of the sample prepared by such FIB processing. At anapproximate center of a sample 30, there were formed, by the irradiationof the ion beam 20 and by the following ion beam irradiation with theinclination of the sample, a rectangular recess, an L-shaped recessconnected to the rectangular recess and a slat-shaped sample piece ofwhich bottom is detached by an ion beam 21 after the inclination of thesample and which is partially connected to the sample.

Then the inclined sample was returned to the original state, then theprobe was contacted with the sample piece partially connected to thesample, and a film was formed in the contact position of the probe andthe sample piece by introducing a gas from the gas introducing means andexecuting an FIB beam irradiation, thereby adhering the probe to thesample piece. Thereafter the partial connecting portion between thesample piece and the sample was FIB processed to cut off the samplepiece from the sample, and the probe was elevated to lift the samplepiece together with the probe. FIG. 5B is a schematic view showing thussectioned sample piece. The sample piece partially connected to thesample 30 as shown in FIG. 5A was adhered to the probe 40, thenseparated from the sample 30 by cutting off the connecting portion, andwas lifted as a sample piece 31. In this operation, it was confirmedthat the probe was maintained at a temperature of about −100° C., thesame as that of the sample. For film formation, there was employed a gasof tungsten carbonyl (W(CO)₆).

Then the sample piece on the probe was moved, together with the probe,onto the sample table, contacted with the sample table under temperaturecontrol and adhered to the sample table by a gas introduction as in thecase of probe adhesion, and the probe used for moving the sample piecewas cut off by an FIB processing. FIG. 5C is a schematic view showingthe sample table on which the sample piece was adhered. The sample piece31 was fixed by the sample table 50 by a deposition film 60.

Then a finish processing was conducted. In this case, a thin piece wasprepared for TEM observation.

In such finish processing, the processing was conducted with graduallyweaker conditions, and, during the processing, the sample surface underprocessing was SIM observed from time to time for confirming whether theprocessing proceeded close to the desired position. Finally, forimproving the precision of cross sectional processing, the crosssectional processing portion was further worked under a weak conditionsimilar to that in the SIM observation.

In the present example, as explained in the foregoing, the FIBprocessing was conducted while the sample was maintained at −100° C., sothat the cross sectional processing could be executed without deformingof the liquid crystal layer during the processing. After a thin slicefor TEM was prepared in this manner, the sample was returned to thenormal temperature and was TEM observed, whereby a cross section of thepolymer layer structure on the substrate could be observed.

Example 2

In the present example, a cross sectional evaluation of polymerparticles (polystyrene) prepared on a PET substrate was executed in thefollowing procedure.

The apparatus shown in FIG. 1 was set at a temperature of about 10° C.,and the sample and the probe were temperature controlled. After the tipof the probe was contacted with the polymer particle to be evaluated asin Example 1, and the polymer particle and the probe were adhered by agas introduction and an FIB irradiation. FIG. 6A is a schematic viewshowing the probe 40 and the sample 31 thus adhered, and a depositionfilm 60. Then the polymer particle was moved together with the probe,and FIB processing was executed at the cross sectional observationportion. FIG. 6B is a schematic view showing the probe 40 and the sample31 after the cross sectional processing.

After cross sectional processing of the polymer particle in this manner,the sample was taken out together with the probe and was subjected to across sectional SEM observation and an elemental analysis in anotherevaluation apparatus. At first the SEM observation proved that thepolymer particle had a uniform interior without a bubble. There wereemployed conditions of an acceleration voltage of 15 kV and amagnification up to about 30,000.

Then, during the SEM observation, specific X-ray emitted from the crosssection of the sample 31 was acquired to prepare a mapped image(elemental analysis), thereby proving that aluminum was dispersed in thepolymer.

In the foregoing, there has been explained a method of evaluating across section of a sample, but the present invention is not limitedthereto. For example, the present invention includes a configurationwhere a substance deposited to the surface is removed, thereby exposingthe surface to be observed and executing a surface observation.

1. An apparatus for conveying a specimen comprising a probe forconveying a specimen to be observed, and temperature control means forcontrolling a temperature of said probe whereby said sample does notchange during conveyance.
 2. A specimen-obtaining apparatus comprising:a stage for supporting a sample; first temperature control means whichregulates a temperature of said sample; means for isolating a part ofsaid sample; probe moving means for mounting and moving a probe; a probefor obtaining a part of the sample isolated by said isolation means; andsecond temperature control means for controlling a temperature of saidprobe.
 3. A sample processing apparatus comprising: a stage forsupporting a sample; first temperature control means for controlling atemperature of said sample; ion beam generation means for irradiatingsaid sample with an ion beam; detection means for detecting a signalemitted from said sample in response to the irradiation of said ionbeam; a probe for obtaining a part of the sample processed by theirradiation of said ion beam; a sample table for evaluation; secondtemperature control means for controlling a temperature of said probe;and third temperature control means for controlling a temperature ofsaid sample table.
 4. The sample processing apparatus according to claim3, wherein the ion beam generated by said ion beam generation means isused to expose a face to be acquired and said detection means is used toacquire information under conditions that the temperature of said sampleis regulated to a predetermined temperature by said first temperaturecontrol means; and section and attachment of the sample are carried outin a state where the temperature of said probe and sample is adjusted toa predetermined temperature by said first and second temperature controlmeans.
 5. The sample processing apparatus according to claim 3, whereinsaid first and second temperature control means are provided withcooling means for cooling said sample to a temperature equal to or lowerthan a room temperature.
 6. The sample processing apparatus according toclaim 3, wherein said stage, said ion beam generation means, saiddetection means, said probe and said sample table are provided in achamber with a controllable atmosphere, and said apparatus furthercomprises trap means for trapping a gas remaining in said chamber. 7.The sample processing apparatus according to claim 3, wherein said firsttemperature control means includes a temperature-varying system in aportion onto which said sample is fixed; and the apparatus furtherincludes: a sample stage enabling moving or inclining of the samplefixed thereon; a probe stage having a movable tip; a sample table forevaluation; first temperature detection means which is mounted in a partof said temperature-varying system to detect the temperature in thevicinity of the sample fixed to said temperature-varying system; andtemperature control means for controlling temperature of saidtemperature-varying system on the basis of the temperature detected bysaid first temperature detection means, thereby maintaining said sampleat a predetermined temperature.
 8. A sample processing apparatusaccording to claim 7, wherein an ion beam can be irradiated on a lateralsurface of the sample held on said temperature-varying system.
 9. Asample processing apparatus according to claim 7, wherein saidtemperature control means further includes second temperature detectionmeans for directly detecting the temperature of the sample; and displaymeans for displaying the temperature detected by said second temperaturedetection means.
 10. A sample processing apparatus according to claim 9,wherein said temperature control means executes temperature control insaid temperature-varying system on the basis of the temperaturesdetected by said first and second temperature detection means.
 11. Asample processing apparatus according to claim 3, wherein said emittedsignal is a secondary electron or secondary ion.
 12. A sample processingapparatus according to claim 3, wherein said detection means includes afirst detector for detecting secondary electrons and a second detectorfor detecting secondary ions.
 13. A sample processing method comprisingthe steps of: controlling temperature of a sample, a probe and a sampletable; sectioning or processing the sample by irradiating apredetermined portion of the sample with an ion beam from at least twoangular directions relative to a surface of the sample; and connectingsaid probe to a part of said sectioned sample.
 14. A sample evaluatingmethod comprising the steps of: controlling a temperature of a sample, aprobe and a sample table; sectioning or processing the sample byirradiating a predetermined portion of the sample with an ion beam fromat least two angular directions relative to a surface of the sample;connecting said probe to a part of said sectioned sample; isolating saidsectioned sample to which said probe has been attached; attaching theisolated sample to said sample table using the probe; cutting off theprobe; and irradiating the sample attached to said sample table with anevaluation beam for evaluation to obtain from an emitted signal an imageof a cross-sectioned face of the sample generated by the sectioning orprocessing step.
 15. A conveying apparatus comprising: a conveyingmember for conveying a sample for observation under an electronmicroscope; and temperature control means which regulates a temperatureof said conveying member; wherein said temperature control meansregulates the temperature of said sample in such a manner that it doesnot change before and after the conveyance.